This document discusses physical and chemical properties of matter. Physical properties can be observed or measured without changing the identity of the substance, such as boiling point, melting point, color, odor, and hardness. Physical changes alter the physical form of matter without changing its chemical makeup, like boiling, freezing, or bending. Chemical properties describe a substance's ability to undergo chemical reactions, like flammability or reactivity. Chemical changes result in one or more new substances forming, indicated by signs like color changes, gas production, or precipitation. The key difference is that physical changes do not alter the composition of matter, while chemical changes do.